Vehicles incorporating automatic transmissions shift automatically between gears in the transmission in response to changes in the throttle. For example, when a driver adjusts an accelerator pedal, these changes adjust the automatic transmission to find the appropriate gear. There are different types of shifting scenarios including power on/off upshifting and power on/off downshifting. Power On shifting refers to shifting into a higher gear (upshifting) or a lower gear (downshifting) when the accelerator pedal is depressed. Power Off shifting refers to shifting into a higher gear (upshifting) or a lower gear (downshifting) when the accelerator pedal is released.
One form of automatic transmissions utilizes a dual clutch in order to shift between gears. In these dual clutch transmissions, there is commonly an off-going clutch that is engaged to and driving the present gear and an on-coming clutch that is used to engage the gear to be shifted into (upshifting or downshifting). It is necessary to balance torque between the on-coming and off-going clutches in order to provide a smooth shift quality. Some systems utilize a process where the off-going clutch is ramped down to induce a continuous microslip. This microslip is used to determine an appropriate torque to apply to the on-coming clutch. The use of this microslip technique accounts dynamically for engine torque and clutch torque errors as well as I-alpha components.
In commercial vehicles utilizing dual clutch transmissions, it may be desirable to utilize a technique other than a sustained microslip technique. This may additionally be desirable in commercial vehicles having deep start ratios and flexible drivelines as compared to standard automobiles. In commercial vehicles with an off-going gear ratio equal to or greater than 4, a technique other than microslip may also be highly desirable for improving shift quality.